Air conditioning apparatus

ABSTRACT

Apparatus for supplying treated air to an enclosure, including a heat exchanger to which a heat exchange medium flows and a fan arranged to route air to be treated over the heat exchanger in heat transfer relation with the medium. A structure serving as an air passage functions to supply treated air to one or more outlets. The discharge area of the outlets is modulated in response to changes in room temperature, while the speed of the fan remains substantially constant.

United States Patent Eckman et al.

[151 3,682,381 [451 Aug. 8, 1972 [5 AIR CONDITIONING APPARATUS 721 Inventors: Raymond L. Manlius,

David F. Bryans, Cazenovia, both of NY.

[73] Assignee: Carrier Corporation, Syracuse, NY, [22] Filed: July 27, I970 [21] Appl. No.: 58,373

[52] US. Cl. ..236/38, 236/49, 236/78 [51] Int. Cl. ..F24f 11/04 [58] Field of Search ..236/1 B, 38, 49, 78

[56] References Cited UNITED STATES PATENTS 4/1957 Martinson ..236/9 A 1/1940 Locke ..236/1 B 9/1941 McGrath ..236/38 2,664,244 12/1953 Miller ..236/1B 2,783,423 2/1957 Streater ..236/74 UX 3,343,791 9/1967 White ..236/78BX Primary Examiner-Edward J. Michael Attorney-Harry G. Martin, Jr. and J. Raymond Curtin [57] ABSTRACT Apparatus for supplying treated air to an enclosure, including a heat exchanger to which a heat exchange medium flows and a fan arranged to route air to be treated over the heat exchanger in. heat transfer relation with the medium. A structure serving as an air passage functions to supply treated air to one or more outlets. The discharge area of the outlets is modulated I in response to changes in room temperature, while the speed of the fan remains substantially constant.

1 Claim, 2 Drawing Figures minimum I912 3.682.381

Q5 LL O INVENTOR. N I RA ND L. ECKMAN BY DA F. BRYANS ATTORNEY 1 AIR CONDITIONING APPARATUS BACKGROUND OF THE INVENTION This invention relates to an air conditioning apparatus and, more particularly, to an arrangement for controlling the discharge of treated air from said apparatus.

Air conditioning apparatus of the type employing a heat exchange coil to circulate a heat exchange medium therethrough, for example, chilled or warmed water, and having a fan for bringing air to be conditioned into heat transfer relation with the mediumflowing through the coil are well known and widely employed by those skilled in the air conditioning art. Such apparatus are generally referred to as fan coil units.

Fan coil units are employed with central station cooling and heating machinery for conditioning multi-room buildings, such as motels, hotels, and apartments. Such apparatus afford a relatively effective means for simultaneously conditioning a plurality of areas in a common enclosure, while providing individual control by the occupants of each area. In addition, fan coil units are relatively simple to install and to maintain in operating condition and are relatively inexpensive, making such units particularly suitable for low-cost, multiple dwelling housing. However, some problems have been encountered which reduce the overall efficiency and effectiveness of their operation.

For example, on-off cycling of the typical fan coil unit creates annoying sound variances. In addition, an on-off type of control does not provide uniform air distribution. Particularly, temperature variations of a considerable magnitude above and below the room setpoint may be produced in portions of the room, the variations being caused by stratification of the air during the off cycle. Furthermore, it has been determined that a more efficient control of the humidity level, when the apparatus is operating on cooling mode, may be obtained by continuously operating the fan, rather than employing an on-off cycle of operating or modulating the cold water flow to the heat exchange coil.

It is an object of this invention to overcome the problems hereinabove noted by providing a novel air conditioning apparatus.

SUMMARY OF THE INVENTION This invention relates to an air conditioning apparatus and, more particularly, to an improved arrangement for controlling the flow of treated air from such apparatus.

The apparatus includes a heat exchanger adapted to receive a heat exchange medium, such as chilled or warmed water, which may be treated in a central station or other remote location. A fan is operable to route air to be treated over said heat exchange coil in heat transfer relationship with the medium flowing therethrough. A temperature sensing element is installed in the area being treated, and is operable to generate a signal, the magnitude thereof being related to the sensed temperature in the treated area.

The treated air from the heat exchange medium is passed to one or more outlets of the apparatus by a structure serving as an air passage. Each outlet includes means operable to receive the control signal generated by the temperature sensing element and is further operable to modulate the position of the outlet as a function of a sensed temperature.

By varying the position of the outlet to regulate the discharge area through which the treated air passes into the enclosure, the quantity of treated air delivered to the enclosure is modulated to meet specific load requirements. The fan supplying the treated air may thus remain operational at all times, thus obviating the prior art difficulties.

In addition, by decreasing the discharge area of the outlet, as the requirement for treated air is diminished, the static pressure in the air passage is increased. As is well known, velocity is a function of static pressure. Thus, by increasing the static pressure, the velocity of the treated air discharged into the enclosure is increased. By increasing the velocity of the air discharged into the enclosure, the momentum of the air is maintained substantially constant, regardless of the reduction in the quantity of air being discharged. As conditions change, so that a greater quantity of treated air is required, the area of the outlet will increase. Although the static pressure and thus the velocity will be concurrently decreased, the momentum will remain substantially constant due to the increased supply of treated air.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, there is shown a preferred embodiment of an air conditioning apparatus including the invention disclosed herein.

Reference numeral 10 indicates an area in an enclosure which is to be treated by having air at a predetermined temperature discharged therein. Although it is within the scope of the invention to have only one such area or room being conditioned, it should be understood several rooms, each employing apparatus embodying the subject of this invention, may be conditioned simultaneously.

The illustrated embodiment includes an air conditioning apparatus 12. Apparatus 12 includes a heat exchange coil 13 to which a heat exchange medium, such as cold or warm water, is supplied via conduit 14. The heat exchange medium is supplied at a predetermined temperature which is regulated by central station refrigeration machinery (not shown). The heat exchange medium is returned to the central station machinery via conduit 15. Fan 16 operatively connected to a motor routes ambient air over the heat exchange coil in heat transfer relation therewith. The ambient air is treated by passing in heat transfer relation with the heat exchange medium flowing through the coil.

The air conditioning apparatus 12 is mounted in a structure 17 which defines an air passage through which the treated air is supplied to at least one outlet 18 for delivery to the room or enclosure being treated. Damper l9 regulates the passage of air to the enclosure from outlet 18. The manner in which damper 19 is controlled in accordance with the invention disclosed herein shall be morefully explained hereinafter.

As noted hereinbefore, it is desirable to regulate the quantity of treated air being supplied to the enclosure in accordance with the load requirements thereof. By regulating the position of damper 19 to vary the discharge area from outlet 18, it is possible to modulate the supply of treated air as is desired, while maintaining fan 16 continuously operative, thereby eliminating the prior art difficulties noted hereinbefore.

It should be understood that the speed of the fan is maintained to provide the necessary supply of treated air to meet the maximum load requirements for which the apparatus 12 is designed to handle.

Furthermore, the novel arrangement herein disclosed operates to maintain the momentum of the treated air discharged into the enclosure substantially constant by increasing the velocity of the air when the quantity thereof has been reduced; and similarly, decreasing the velocity of the air when the quantity of the air being discharged has been increased.

The control circuit provided for obtaining the desirable features hereinbefore described is merely illustrative, and other control schemes that might perform a similar function may be employed in lieu thereof.

The control circuit includes a voltage transformer operable to reduce the line voltage represented by lines L and L to a smaller voltage for control purposes. The voltage transformer includes a primary winding 20 and a secondary winding 21. Preferably, the current flowing through lines L and L is 60 cycle alternating current. Since the control circuit, to be more fully explained herein, utilizes solid state components operable on direct current, a full wave diode rectifier circuit 22 is provided as a source of DC voltage, the DC voltage source being represented by +E, and E,. Resistors 76 and 77 and capacitors 68 and 69 are provided to filter the DC voltage.

Thermostat elements 23 and 24 are connected in series with the source of DC voltage. Element 24 is preferably a variable resistance element, such as a potentiometer, that may be selectively regulated by the occupant to obtain a desired temperature in the enclosure. Element 23 is preferably a NTC thermistor positioned to sense the temperature of the air in the enclosure. Elements 23 and 24 operate in combination to provide a variable voltage signal. When the temperature of the enclosure is above the setpoint established by thermal element 24, the voltage signal is of a relatively large magnitude and of a positive polarity, whereas when the temperature is below the setpoint, the voltage signal is of a relatively large magnitude and of a negative polarity.

The voltage signal from elements 23 and 24 is supplied to a first input of operational amplifier 26, through resistor 25. The manner in which operational amplifier 26 functions shall more fully explained hereinafter. Operational amplifier 26 also has supplied thereto a +E voltage through line 70 and a -E, voltage through line 71.

Connected to the output of the operational amplifier is a first diode 27 and a second diode 28. Diode 28 permits only passage of a negative supply voltage, whereas diode 27 only permits passage of a positive voltage signal.

Connected in series with diode 27 is relay coil 32, the energization thereof operating to close normally open switch 33. Connected in series with diode 28 is relay coil 30, the energization thereof operating to close normally open switch 31.

Connected to the output from either switch 31 or switch 33 is double-pole, double throw switch 34. Switch 34 includes a first arm 39 which selectively connects either terminal 37 or terminal 38 in the circuit. Terminal 37 is connected into the circuit when the apparatus is providing relatively cold air, whereas terminal 38 is connected in the circuit when the apparatus is providing relatively warm air. Switch 34 also includes arm 40 which selectively places either terminal 35 or terminal 36 into the circuit. Terminal 35 is placed in the circuit when the apparatus is providing relatively cold air, and terminal 36 is placed in the circuit when the apparatus is providing relatively warm air.

Switch 34 may be controlled manually or may be operated automatically by means such as a bimetal switch which would be placed in heat transfer relation with the heat exchange medium flowing to heat exchange coil 13.

Connected in series with switch 34 are windings 41 and 42 of a reversible motor 43, connected to the source of alternating current as represented by lines L and L The energization of winding 41, prior to the energization of winding 42, will actuate the motor so that the damper will rotate in a counterclockwise direction so that the discharge area of outlet 18 is increased.

Conversely, the energization of winding 42, prior to the energization of winding 41, will actuate motor 43 so that damper 19 will rotate in a clockwise direction to decrease the discharge area from outlet 18. Motor 43 is operatively connected to damper 19 via shaft 44. Capacitor 65 is included between windings 41 and 42 to establish the necessary phase displacement therebetween.

Operatively connected to shaft 44 is shaft 47. Shaft 47 has movably connected thereto wiper 46 of potentiometer 45. The rotation of shaft 44 so as to decrease the area of discharge outlet 18 will rotate wiper 46 in a clockwise direction, whereas rotation of shaft 44 so as to increase the area of discharge outlet 18 will rotate wiper 46 in a counterclockwise direction.

Connected in series with potentiometer 45 is a second double-pole, double throw switch 50. Switch 50 includes arm 51 and arm 52. As shown by the solid line, arms 51 and 52 are positioned for cooling mode operation. As shown by the dotted lines of the Figure, arms 51 and 52 are positioned for heating mode operation. The operation of switch 50 may be manually or automatically regulated.

Connected in series with switch 50 and potentiometer 45 are fixed resistors 48 and 49. Lines 66 and 67 are connected to the source of rectified DC voltage so as to bring the supply voltage to potentiometer 45.

Depending upon the mode of operation and the position of wiper 46 as controlled by the position of damper 19, either a positive polarity or a negative polarity voltage signal, the signal being proportional to the position of the damper, will be supplied via line 72 and resistor 54 to a second input of operational amplifier 26.

The operational amplifier compares the voltage signal regulated by potentiometer 45 to the voltage signal regulated by thermal elements 23 and 24, to operate motor 43 so that the position of damper 19 is modulated in response to the temperature of the enclosure.

To better understand the manner in which the control circuit operates in accordance with the invention, assume that cooling mode operation is desired and that the temperature of the enclosure is above the setpoint.

The magnitude of the variable voltage control signal controlled by thermal elements 23 and 24 will be sufficient to cause operational amplifier 26 to pass a positive polarity voltage signal from line 70 to line 29.

The +E, voltage signal will pass through diode 27 and energize coil 32, thereby closing switch 33.

When switch 33 closes, line voltage represented by L and L will pass through arm 39 of double-pole, double throw switch 34 which is in contact with terminal 37, thereby energizing coil 41 of motor 43. The motor will thus be actuated to turn shaft 44 in a counterclockwise direction to open damper 19.

As damper 19 moves in a counterclockwise direction, wiper 46 of potentiometer 45 simultaneously moves in the same direction, the position thereof being related to the position of the damper. Double-pole, double throw switch 50 is set for cooling mode operation. Therefore, arm 52 is in a position in which the +E control signal will pass through resistor 49 and wiper 46 to line 72, the magnitude of the signal being proportional to the position of the damper. When the position of the damper has reached an equilibrium point in relation to the temperature of the enclosure, the magnitude of the control signal in line 72, as determined by the position of wiper 46, will be equal to the magnitude of the variable voltage control signal regulated by thermal elements 23 and 24 and will thus place operational amplifier 26 in a nonconducting state, turning off motor 43.

If the temperature of the enclosure has fallen below the setpoint during cooling mode operation, the mag nitude of the variable voltage control signal supplied to operational amplifier 26 will be such that a negative polarity control signal will pass from line 71 to line 29.

The E control signal will pass through diode 28, thereby energizing relay 30, thus closing switch 31.

When switch 31 closes, line voltage will pass to terminal 35 of double-pole, double throw switch 34 and will flow through arm 40 to coil 42, thus energizing motor 43 to cause shaft 44 to rotate in a clockwise direction.

Wiper 46 of potentiometer 45 will simultaneously move in a clockwise direction. Arm 51 of double-pole, double throw switch 50 will provide a E voltage signal through line 66 and resistor 48 to the wiper. The magnitude of the voltage signal will be determined by the position of the wiper relative to the resistance elements of potentiometer 45. The variable voltage signal will then flow through line 72 to resistor 54 and operational amplifier 26. When the magnitude thereof is equal to the magnitude of the variable control signal regulated by thermal elements 23 and 24, operational amplifier 26 will become non-conductive.

Assume now that the enclosure requires heating. Double-pole, double throw switch 34 will be set so that arm 39 will be in contact with terminal 38, and arm 40 will be in contact with terminal 36. If the temperature of the enclosure is below the setpoint, the variable voltage control signal passing through resistor 25 to operational amplifier 26 will be of a magnitude to provide a negative polarity control signal through line 71 to line 29. The E voltage signal will pass through diode 28, thereby energizing coil 30 and closing switch 31.

Line voltage will then pass through terminal 35, terminal 38, and arm 39, to energize coil 41, thereby caus ing motor 43 to rotate in a counterclockwise direction to open damper 19 as is desired to obtain a greater quantity of treated air. Wiper 46 will simultaneously move in a counterclockwise direction. Double-pole, double throw switch 50 is set for heating mode operation. The E,, voltage signal will pass through line 66, arm 51, and resistor 49 to wiper 46. The variable voltage signal thus generated will then pass through line 72 to resistor 54, terminating at operational amplifier 26.

If, during heating mode operation, the temperature of the enclosure rises above the setpoint, the control circuit will operate to close the damper 19 to the proper position for the required quantity of treated warm air.

As shown in the Figure, it may be desirable to regulate the position of more than one damper in response to the sensed temperature in the enclosure. Although not shown, for means of clarity, structure 17 would include an extension serving as an air passage to a second outlet. Such a modification would be particularly employed in multi-room enclosures such as an apartment in an apartment building.

Line would supply the variable control signal from thermal elements 23 and 24 to a second operational amplifier 26', having resistor 25 connected to its first input and resistor 54 connected to its second input. Switch 81 may be included so that one damper may be inoperable while the other damper is operable.

The remainder of the control circuit for varying the position of the damper in response to the variable control signal is identical to that previously described and has not been shown for purposes of clarity. It should be understood that any number of such dampers, having a single source of treated air, may be similarly controlled.

The invention disclosed herein will permit regulation of the quantity of treated air passing to an enclosure in proportion to the temperature thereof while maintaining the momentum of the treated air being discharged substantially constant. By regulating the position of the damper to control the quantity of treated air being discharged into the enclosure, the fan 16 may remain operative continuously, thus eliminating the prior art difficulties.

If desired, sound attenuating material may be installed on the inner surfaces of the air passage and on the damper.

While we have described and illustrated a preferred embodiment of our invention, it should be understood that the invention is not limited thereto but may be otherwise embodied within the scope of the following claims.

We claim:

1. Air conditioning apparatus for regulating the temperature of air circulating within an enclosure comprismg:

A. a structure serving as a housing;

B. heat exchange means disposed in said housing through which a heat exchange medium is passed;

C. a fan for supplying a quantity of air flow in heat transfer relation with the heat exchange medium passing through said heat exchange means, a constant speed electric motor operatively connected to said fan to rotate said fan at a constant speed;

D. means defining an outlet from said housing through which the treated air is discharged into the enclosure, said heat exchange means being disposed in the housing between the outlet and the fan;

E. means for sensing the temperature of the air in the enclosure and generating a variable control signal, the magnitude thereof being related to the sensed temperature; and

F. means for receiving the variable control signal and operating in response to said signal to vary the discharge area of said outlet means, said means serving to increase the discharge area when conditions inthe enclosure as indicated by the variable control signal require a greater quantity of treated air and serving to decrease the discharge area when conditions in the enclosure as indicated by the variable control signal require a lesser quantity of treated air, static pressure in the housing increasing as the discharge area is decreased and decreasing as the discharge area is increased so that the velocity of the treated air discharged from said outlet is increased as the quantity of air discharged is decreased and is decreased as the quantity of air discharged from said outlet is increased to maintain a substantially constant discharge momentum; said means for receiving said variable control signal including an operational amplifier, and first and second diodes, said first diode pemiitting only passage of a positive polarity voltage and said second diode permitting only passage of a negative polarity voltage.

patent 3,687 Dated "August 8, 1972 Raymond L. Eckman et a1. Inventor(s) v It is certified that. error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the grant (only) insert the Sheet of drawings Showing Figures and Column 6,71ine 26, cancel "Figure" and insert drawing Signed'and sealed this 9th day of July 1974.

(SEAL) Attest:

MCCOY M. GIBSON, JR. I c. MARSHALL DANN Attesting Officer Commissioner of Patents M PO'WSO uscoMM-Dc 60310-P69 v U.S. GOVERNMENT PIINT'NG OFFICE Z l", 0-368-334. 

1. Air conditioning apparatus for regulating the temperature of air circulating within an enclosure comprising: A. a structure serving as a housing; B. heat exchange means disposed in said housing through which a heat exchange medium is passed; C. a fan for supplying a quantity of air flow in heat transfer relation with the heat exchange medium passing through said heat exchange means, a constant speed electric motor operatively connected to said fan to rotate said fan at a constant speed; D. means defining an outlet from said housing through which the treated air is discharged into the enclosure, said heat exchange means being disposed in the housing between the outlet and the fan; E. means for sensing the temperature of the air in the enclosure and generating a variable control signal, the magnitude thereof being related to the sensed temperature; and F. means for receiving the variable control signal and operating in response to said signal to vary the discharge area of said outlet means, said means serving to increase the discharge area when conditions in the enclosure as indicated by the variable control signal require a greater quantity of treated air and serving to decrease the discharge area when conditions in the enclosure as indicated by the variable control signal require a lesser quantity of treated air, static pressure in the housing increasing as the discharge area is decreased and decreasing as the discharge area is increased so that the velocity of the treated air discharged from said outlet is increased as the quantity of air discharged is decreased and is decreased as the quantity of air discharged from said outlet is increased to maintain a substantially constant discharge momentum; said means for receiving said variable control signal including an operational amplifier, and first and second diodes, said first diode permitting only passage of a positive polarity voltage and said second diode permitting only passage of a negative polarity voltage. 